They are reacting as they have been trained to react; war is hell, the army build in defense mechanisms like this to ensure soldiers can fight (emotional detachment, jock attitude), they also ingrain absolute discipline to try and avoid scenario's exactly like this.

EDIT: supporting evidence - read some military training manuals. They basically detail the attitude training attempts to instill in a soldier. shrug this is common to pretty much every standing army in the history of ever :) (emotional detachment especially)